The present invention relates generally to leadframes for use in semiconductor packages. More specifically, the invention relates to fuse flames and programmable fuse flames which are fabricated such that internal connections can be made within a semiconductor package and support for the internal connections comes directly from the semiconductor die.
In the field of semiconductor packaging the cost of the components making up the package and the complexity of the manufacturing process are of major concern. Any improvement which simplifies the manufacturing process, improves the durability of the package, or reduces the cost of the components making up a semiconductor package can provide a significant commercial advantage. Also, in order to reduce the amount of material required to produce a given package and reduce the space required by the finished semiconductor package, packages are being made smaller and thinner. Because of these factors, the packaging of semiconductors continuously demands smaller and more cost effective designs and methods for producing semiconductor packages.
In response to these demands, designers in the field of semiconductor packaging have developed multi-chip semiconductor packages. Multi-chip packages include not only semiconductor packages containing more than one die but also so-called hybrid packages which incorporate components based on technology other than semiconductor technology. Representative components include resistors, inductors, capacitors and oscillating crystals. The aforementioned multi-chip packages have in some cases reduced the size and material needed for the packages while expanding their capabilities.
Fabrication methods for single chip semiconductor packages are well known to those skilled in the art of semiconductor packaging and are generally relatively straight forward. Most commonly, a lead frame having an array of electrically conductive leads is used to electrically connect (by way of bonding wires) the internal elements of the single chip to external elements. The lead frame must be supported during both the attachment of the bonding wires and encapsulation of the internal components. To provide the required support, the array of electrically conductive leads are supportably held together by a rail that extends around the periphery. Once the leads are electrically connected to the internal elements, an encapsulant material is formed surrounding the chip and a substantial portion of the lead frame. At this point, the leads no longer require support from the rail which is subsequently trimmed away.
In some situations it is desirable to provide a completely internal connection that is external to a die. By way of example, in multi-chip packages it is common to electrically connect a contact pad of a first semiconductor die with a contact pad of a second semiconductor die. Traditionally, it has been difficult to use lead frames to accomplish such internal connections since the internal lead must be supported in some manner during various processing steps. Thus, current solutions generally require additional fabrication steps such as forming traces on a substrate and/or adding additional components such as a small printed circuit board to provide the necessary traces and support. While operable, these solutions generally result in additional steps, increased material requirements, reliability issues and, inevitably, higher costs. Accordingly, it would be advantageous to provide an economical mechanism that permits lead frames to be used to make internal connections in an economical manner.